Trump’s cognitive screening has limits

Measures of cognitive abilities range from brief screening tools designed to help identify individuals who may be in need of further evaluation, to detailed assessments of multiple cognitive functions that aid in clinical diagnosis. It is important to understand some of the issues and limitations involved in the use of cognitive screening tests.

Screening tests are designed to be brief and to help raise the likelihood of detecting a true abnormality. They are not designed to be diagnostic. In cases of severe dementia, a cognitive screening test may be all that is needed to document impairment, although in less severe cases, screening test results may be normal, when in fact an underlying cognitive disorder might be present that may only be detected through a more thorough neuropsychological evaluation.

Two popular cognitive screening tests (the Mini Mental State Examination and the Montreal Cognitive Assessment) are rudimentary. They include simple items designed to detect obvious abnormalities in orientation (time, place, person) and aspects of language, attention and memory. Both tests have a maximum of 30 points, and although there are levels of impairment, there really are no “above average” or “excellent” scores. Although these screening tests are sensitive to full-blown dementia, they are not sensitive to subtle impairment, and they do not evaluate all cognitive domains. For example, there is no real assessment of reasoning, thinking speed, or problem solving in these brief screening tests, and the memory tasks are cursory and simple. As such, it is not difficult for people to obtain scores in the “normal” range, even in the presence of brain dysfunction. In fact, it has been found that up to 14% of patients with Alzheimer’s disease may have cognitive screening scores in the normal range.

William Perry, executive director National Academy of Neuropsychology Denver